Variable radii flanges for mechanically retained crush tubes

ABSTRACT

A support assembly for an assembly comprised of an extruded member that defines a cavity, the member including an opening having a plurality of sides, and a crush tube inserted into the cavity of the member and mechanically retained in the member at or near a desired location by flanging the sides of the opening into an open end of the crush tube.

BACKGROUND

Extruded hollow bars may be used as members in a support assembly. Acavity in a support assembly member may include a crush tube to provideadditional support, bear a mechanical load at an attachment point of themember to a support assembly, etc. It is generally desired to retain acrush tube at or near a particular location in the cavity. For example,it may be desired to retain the crush tube at or near an opening in thesupport member. However, stresses at or near the opening can causedefects such as cracks and the like to form in the member, e.g., whenthe member is made of extruded aluminum. Such defects may in turncompromise the support assembly.

DRAWINGS

FIG. 1 is a perspective view of an exemplary support assembly.

FIG. 2 is a top perspective view of an exemplary top surface of a membershowing an exemplary opening.

FIG. 3A is a perspective view of an exemplary top surface of a memberafter the opening in the member has been flanged.

FIG. 3B is a perspective view of exemplary bottom surface of a member.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of an exemplary support assembly 10. Thesupport assembly 10 includes a member 12 formed by being extruded alonga longitudinal axis A. The member 12 defines a cavity 14. The member 12has a substantially rectangular cross-section, and includes asubstantially planar top surface 16. The cavity 14 may accommodate oneor more crush tubes 36, e.g., as further shown in FIG. 1, two crushtubes 36 have been inserted into the cavity 14 of the member 12 toprovide localized strength and support.

As seen in FIG. 2, the top surface 16 of the member 12 includes anopening 18 to the cavity 14. The opening 18 includes a plurality ofarcuate sides, each side forming an arc defined by a portion of one of aplurality of circles having a center point D. Accordingly, a first side20 is defined by a first curvature. A point F is substantially midwaybetween endpoints of the side 20. A tangent line G at the point F issubstantially parallel to the longitudinal axis A of the member 12. Theopening 18 also includes a second side 22 that has a second curvature. Apoint H is substantially midway between endpoints of the side 22. Atangent line K at the point H is substantially perpendicular to thelongitudinal axis A. Further, in the example of FIG. 2, the opening 18has a third side 24 that diametrically opposes the first side 20 aboutan axis, and a fourth side 26 that diametrically opposes the second side22 about an axis.

Still referring to the example of FIG. 2, arcs of a first circle B,define the first side 20 and third side 24 of the opening 18. Arcs of asecond circle C define the second side 22 and fourth side 26 of theopening 18. The first circle B and second circle C have a common centerpoint D, with the first circle having a first radius R₁, and the secondcircle having a second radius R₂. The two radii R₁, R₂ differ in length,e.g., as shown in FIG. 2, the first radius R₁ is longer than the secondradius R₂.

In addition, the opening 18 in member 12 includes connecting sides 28,30, 32 and 34. Fifth side 28, which connects fourth side 26 and firstside 20, has a convex curvature relative to fourth side 26 and firstside 20. Sixth side 30, seventh side 32 and eighth side 34 connect firstside 20 and second side 22, second side 22 and third side 24, and thirdside 24 and fourth side 26, respectively. Sixth side 30, seventh side 32and eighth side 34 are likewise convex relative to the sides theyconnect. Moreover, the fifth side 28, sixth side, 30, seventh side 32and eighth side 34 of opening 18 have a third curvature, and are definedby arcs of a circle E having a radius R₃. In general, the radius R₃ isshorter than either of the radii R₁, R₂, e.g., half a length or less ofthe other two radii. For example, the radius R₃ may have a lengthdefined by the formula:

R ₃=(R ₁ −R ₂)/Z,

where R₂ is a length of the second radius, R₁ is the length of the firstradius, and Z is a distance coefficient. A value for Z may beempirically determined. For example, in one embodiment, a value of Z=0.8has been found to provide a radius R₃ whereby cracks and fractures inthe member 12 are prevented.

Returning to FIG. 1, the cavity 14 of member 12 may be adapted to allowone or more crush tubes 36 or other suitable elements to be insertedinto, fitted through, or otherwise placed in the member 12. The crushtubes 36 provide member 12 with localized stiffness and strength so thatthe support assembly 10 can better support loads, among other things. Inthe example of FIG. 1, the crush tubes 36 are inserted into cavity 14 ofmember 12, and under openings 18. Once a crush tube 36 is positionedwith respect to an opening 18, the opening 18 may be subjected to aflanging operation so that the sides 20, 22, 24, 26, 28, 30 and 32 arecurved into an open end 38 of the crush tube 36 to mechanically retainthe crush tube 36 at or near a desired location of member 12. The openend 38 of the crush tube 36 will generally have a diameter slightlylarger than first circle B. Accordingly, as discussed below with respectto FIG. 3B, when the opening 18 is flanged, the sides 20, 22, 24, 26,28, 30 and 32 of opening 18 of member 12 form flanges in the open end 38of crush tube 36 that maintain the crush tube at or near the desiredlocation.

FIG. 3A is a perspective view of the top surface 16 of the member 12after the opening 18 has been flanged, creating flanges 42, 44, 46, and48, respectively formed at each of the sides 20, 22, 24, and 26. Theflanges 42, 44, 46, and 48 secure the crush tube 36 at or near a desiredlocation in the member 12. As FIG. 3A illustrates, second side 22 ofopening 18 extends to a first depth into the open end of crush tube 36,further than a second depth to which the first side 20 extends, wherebythe flange 44 has a first curvature that is greater than a secondcurvature of the flange 42. Similarly, the flange 48, formed at the side26, extends into the opening 18 at roughly the first depth of the flange44, and at roughly the first curvature, whereas the flange 46 extendsinto the opening 18 at roughly the second depth. This difference inflange curvatures and depths is a result of the radius R₂ being shorterthan the radius R₁, as described above.

FIG. 3B is a perspective view of a bottom surface 40 of the member 12.From this view, the open end 38 of crush tube 36 is shown, as are sides22, 24 and 26 of opening 18. After the flanging operation, the firstside 20 forms a first flange 42, the second side 22 forms a secondflange 44, the third side 24 forms a third flange 46, and the forth side26 forms a fourth flange 48, which mechanically retain crush tube 36.

As used herein, the adverb “substantially” modifying an adjective meansthat a shape or structure may deviate from an exact described geometrybecause of imperfections in materials, machining, manufacturing, etc.

In the drawings, the same reference numbers indicate the same elements.Further, some or all of these elements could be changed. Accordingly, itis to be understood that the above description is intended to beillustrative and not restrictive. Many embodiments and applicationsother than the examples provided would be apparent to those of skill inthe art upon reading the above description. The scope of the inventionshould be determined, not with reference to the above description, butshould instead be determined with reference to the appended claims,along with the full scope of equivalents to which such claims areentitled. It is anticipated and intended that future developments willoccur in the arts discussed herein, and that the disclosed systems andmethods will be incorporated into such future embodiments. In sum, itshould be understood that the invention is capable of modification andvariation and is limited only by the following claims.

All terms used in the claims are intended to be given their ordinarymeaning as understood by those skilled in the art unless an explicitindication to the contrary is made herein. In particular, use of thesingular articles such as “a,” “the,” “said,” etc. should be read torecite one or more of the indicated elements unless a claim recites anexplicit limitation to the contrary.

1. A support assembly comprising: a member extruded along an axis anddefining a cavity; an opening extending through the member into thecavity, the opening having a first side with a first curvature, and asecond side with a second curvature; a crush tube having an open end,the crush tube inserted into the cavity with the open end located underthe opening; wherein when the opening is flanged, the first side forms afirst flange in the open end of the crush tube and the second side formsa second flange in the open end of the crush tube, thereby retaining thecrush tube at or near a desired location.
 2. The support assembly ofclaim 1, wherein the first flange extends into the open end of the crushtube to a first depth and the second flange extends into the open end ofthe crush tube to a second depth.
 3. The support assembly of claim 2,wherein the first depth is less than the second depth.
 4. The supportassembly of claim Error! Reference source not found., wherein the firstflange includes a first flange surface having a first curvature and thesecond flange includes a second flange surface having a secondcurvature.
 5. The support assembly of claim Error! Reference source notfound., wherein the plurality of sides includes a fifth side having athird curvature.
 6. The support assembly of claim 5, wherein the thirdcurvature is convex with respect to each of the first and secondcurvatures.
 7. The support assembly of claim 5, wherein the fifth sideconnects the first side and the second side.
 8. The support assembly ofclaim 7, wherein the first and second curvatures are defined byrespective first and second radii of first and second circles, the firstand second circles having a same center point, and further wherein thethird curvature is an arc of a third circle, a length of a radius R₃ ofthe third circle being defined according to the formula R₃=(R₁−R₂)/Z,where R₂ is a length of the second radius, R₁ is a length of the firstradius, and Z is a distance coefficient.
 9. The support assembly ofclaim 8, wherein Z=0.8.
 10. The support assembly of claim Error!Reference source not found., wherein the first and second curvatures aredefined by respective first and second radii of first and secondcircles, the first and second circles having a same center point. 11.The support assembly of claim 10, wherein the opening further includes athird side and a fourth side, the third side opposing the first sidegenerally parallel to the axis of extrusion, and the fourth sideopposing the second side generally perpendicular to the axis ofextrusion.
 12. The support assembly of claim Error! Reference source notfound., wherein the member is composed of aluminum.
 13. The supportassembly of claim Error! Reference source not found., having a generallyrectangular cross-section.